Wednesday, 7 December 2011

For and against charters

It being useful to develop the best possible argument against a position you support, here's my best case against New Zealand moving towards the use of charter schools. I'm not convinced by this case. Or, at least I don't think I am. Let's see if I've convinced myself by the end of the argument.

- Begin Advocatus Diaboli -

First, we have to recognize that the New Zealand school system is, on the whole, pretty good as compared to the American school system. Not always and everywhere, but on average. That isn't to say that we can't have improvements. But we have to keep in mind that a lot of the gains found in charter schools in the U.S. are measured against a counterfactual of abysmal urban public schools that compare poorly with some of Dante's circles of hell. Here's a fine description of one such nightmare case. That the enthusiastic young teacher there was able to flip over to a charter school, along with some of the students, produces real gains, both for the students who flip, and for the average quality of those engaged in teaching. The worst US public schools drive the best teachers out of teaching; the Charters give them an option where those who'd rock the boat against horrible school principals and stultifying union rules can flourish.

But are any New Zealand public schools really that bad? If the worst New Zealand public schools don't come within cooie of those American schools, we'd be overestimating the potential gains here from adopting charters. Sure, we can find a few isolated cases where the school principal condoned or covered up horrible bullying. But the worst here just doesn't match the worst there (though I invite readers to show me otherwise).

Further, it's really hard to pin down the gains from American charter schools. Sure, those quasi-experimental studies I cited yesterday are nice. But there's a meta-selection issue: the only schools that use lottery for entry are the really successful charter schools that are oversubscribed. You can identify the gains to the students who make it from the public schools into those schools by that method, but you shouldn't extrapolate from those gains to the average potential gains from widespread use of charters. Then, you have to go to some of the estimates of the overall effects of charter schools, and the empirics there are, frankly, a mess. Selection issues are all over the place. Where do new charters open? Where the worst public schools are as that's where parents want to get their kids out. Which kids flip? Those whose parents care more. Taking average cohort performance across public and charter schools doesn't work if charters disproportionately pick up the better kids from the worst areas, but it's not immediately clear whether that helps or hurts charters' performance stats. And so we find all kinds of studies showing little effect in the aggregate, or strong heterogeneity in results across different charters.

Finally, many of the gains from charters are already available in New Zealand in the form of Integrated Schools - state-funded schools established for a special purpose or with a special mission, but that are restricted to cover the national curriculum. Those aren't impossible to open. What's then gained by allowing entry to those who would perhaps eschew the national curriculum in favour of weird stuff? Yes, it's possible to improve on NCEA, and the best charters will. And, sure, there are already religious integrated schools using public funds to provide a religious message. Brian Tamaki's Destiny Church even runs one. But do we really want Tamaki released from requirements to nominally adhere to the national curriculum?

In the best case, charter schools open in neighbourhoods where zoning keeps poor kids stuck in underperforming schools, parents send their kids there, and public schools are forced to lift their game or suffer enrolment drops, funding drops, and downsizing or closure. And so everything's great. But the more likely case, depending entirely on how the regulations are set up, is that those charters pull the better students from the worst schools. Those better students do fare better in the charter schools. But those left behind fare worse as the public schools remain the residual claimant on the worst cases - the disruptive students that the public school system, for better or worse, cannot help but keep integrated into mainstream classrooms where they ruin outcomes for others. Those students become a greater proportion of those left in the public schools, further depressing outcomes for decent students whose parents just don't care enough to send them over to the charter school; cohort effects matter. Those best students would have made it through regardless, but we worsen outcomes for the middling students of indifferent parents.

- End Advocatus Diaboli -

What do I take from this? Upside gains here, relative to those in the States, are likely to be limited. And, as Seamus noted, it can be tough to extrapolate from US studies to here. But particularly bad outcomes seem unlikely unless we make strong complementary assumptions about parental indifference / parental stupidity and about public school inflexibility in response to the competitive threat.

There will be here, as there are in the States, some charter schools that fail. But even the failures let us learn. Roland Fryer dug into the correlates of charter school success (Freakonomics summary here) and found results a bit divergent from usual teachers' union requests. Input-based solutions like smaller class sizes and higher proportions of staff with teaching certification don't do much. Instead, "frequent teacher feedback, data driven instruction, high-dosage tutoring, increased instructional time, and a relentless focus on academic achievement" explains most differences in outcomes across charter schools. Perhaps it's possible to mandate that state-sector schools here simply adopt best practice. But I worry that that's best-case thinking; the government barely seems able to compel its public schools to disclose student achievement statistics. The threat of student exit seems the best long-term discipline for poorly performing schools. And, as Seamus noted, there's a lot of value in the experimentation to see what methods work here. I find it very plausible that charter schools drawing on tikanga will find more appropriate instruction methods for lower decile Maori groups, and that other approaches will be successful in poorer Pacific Island communities. But we won't know until we try.